title: Circulating platelet-derived and placenta-derived microparticles expose Flt-1 in preeclampsia.
abstract: BACKGROUND
  Flt-1 is secreted by various cells and elevated concentrations are present in preeclampsia affecting vascular function. Microparticles from these cells may expose Flt-1. We evaluated whether Flt-1 is microparticle-associated in preeclampsia, and established the origin of Flt-1-exposing microparticles.
  
  
  METHODS
  The concentration of Flt-1 was measured in samples from preeclamptic patients, pregnant and nonpregnant women by enzyme-linked immunosorbent assay. Microparticles were analyzed by flow cytometry. Western blot determined the different forms of Flt-1.
  
  
  RESULTS
  Noncell bound Flt-1 was elevated in preeclampsia compared to controls. A fraction (5%) was associated with microparticles in preeclampsia. Flt-1-exposing microparticles were increased in preeclampsia compared to normotensive pregnancy (p = 0.02). Full-length Flt-1, was identified in microparticles of platelet and placental origin.
  
  
  CONCLUSIONS
  Full-length Flt-1 is associated with platelet and placenta-derived microparticles. Possibly, the presentation of Flt-1 on the membrane of a microparticle might alter its function, particularly if it acts in synergism with other exposed vasoactive molecules.
authors.affiliation: Department of Obstetrics and Gynaecology, Academic Medical Center, Amsterdam, Netherlands. c.a.lok@ amc.uva.nl
authors.forename: Christine A R
authors.initials: CA
authors.lastname: Lok
authors.forename: Anita N
authors.initials: AN
authors.lastname: Böing
authors.forename: Ian L
authors.initials: IL
authors.lastname: Sargent
authors.forename: Suren R
authors.initials: SR
authors.lastname: Sooranna
authors.forename: Joris A M
authors.initials: JA
authors.lastname: van der Post
authors.forename: Rienk
authors.initials: R
authors.lastname: Nieuwland
authors.forename: Augueste
authors.initials: A
authors.lastname: Sturk
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000097:blood*; D011247:Pregnancy; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000097:blood*
chemical_list: C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1